This project focuses on the reflex control of blood flow to skin. Special emphasis is placed on this regulation when non-thermal reflex drives such as exercise or challenges to blood pressure regulation are in competition with thermal reflex drives, such as internal and skin temperatures. Forearm skin blood flow is measured by plethysmography, skin temperature is controlled with water-perfused suits and exercise is performed on a stationary bicycle ergometer. Specific questions addressed include: Does the reflex response of skin blood flow or of sweat rate to rising skin temperature depend, in an important way, on the level of internal temperature? Does the reflex control of sweat rate parallel that of the cutaneous circulation and can such similarity in control be modified by exercise or the upright posture? Is the reflex thermoregulatory control of skin blood flow during exercise modified by the level of work? Answers to these specific questions should enhance our understanding of the regulation of this potentially large regional circulation and should critically test current models of reflex control of the cutaneous circulation.